With development of wireless communications technologies, services (for example, a high-definition video) requiring an ultra high transmission rate emerge, and load on a wireless communications network becomes increasingly heavy. Device-to-Device (D2D) communication refers to direct communication between terminals without a need of forwarding transmitted data by a base station. The D2D communication not only can relieve load on data transmission of a base station, but also can increase a data transmission rate.
To increase spectrum utilization and make the most of a radio frequency capability of an existing terminal, in a mobile communications system such as Long Term Evolution (LTE), a D2D communications link generally reuses a spectrum resource of an existing communications network. In general, the D2D communications link reuses a resource in a centralized control manner, in which a transmission resource is allocated by a central control device (for example, a base station). FIG. 1 is a schematic structural diagram of D2D communication. As shown in FIG. 1, a central control device (Evolved Node B (eNB)) allocates a transmission resource to a transmit terminal (UE B(Tx) shown in FIG. 1). The transmit terminal UE B uses the transmission resource allocated by the central control device to send, to a receive terminal (UE C, UE D, and UE E shown in FIG. 1) in a broadcast manner, data and control signaling related to the data such as scheduling assignment (SA) information. In broadcast communication, a broadcast sending party sends a data service on a specific resource, and a receiving party receives data on a corresponding resource. Therefore, the transmit terminal needs to first send the control signaling to the receive terminal, so as to instruct the receive terminal to receive resource information of the data, and then send the data to the receive terminal. The transmission resource allocated by the central control device to the transmit terminal includes an SA transmission resource and a data transmission resource, and the central control device needs to notify the transmit terminal of the transmission resource information in time.
In the prior art, a central control device schedules an SA transmission resource by sending an SA scheduling permission command to a transmit terminal, and schedules a data transmission resource by sending a data scheduling permission command to the transmit terminal. A resource scheduling method in the prior art causes high signaling overheads and low efficiency.